A race exists where creating cgroups and also updating the priomap
may result in losing a priomap update. This is because priomap
writers are not protected by rtnl_lock.
Move priority writer into rtnl_lock()/rtnl_unlock().
CC: Neil Horman <nhor...@tuxdriver.com>
Reported-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: John Fastabend <john.r.fastab...@intel.com>
---
net/core/netprio_cgroup.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c
index f65dba3..c75e3f9 100644
--- a/net/core/netprio_cgroup.c
+++ b/net/core/netprio_cgroup.c
@@ -101,12 +101,10 @@ static int write_update_netdev_table(struct net_device
*dev)
u32 max_len;
struct netprio_map *map;
- rtnl_lock();
max_len = atomic_read(&max_prioidx) + 1;
map = rtnl_dereference(dev->priomap);
if (!map || map->priomap_len < max_len)
ret = extend_netdev_table(dev, max_len);
- rtnl_unlock();
return ret;
}
@@ -256,17 +254,17 @@ static int write_priomap(struct cgroup *cgrp, struct
cftype *cft,
if (!dev)
goto out_free_devname;
+ rtnl_lock();
ret = write_update_netdev_table(dev);
if (ret < 0)
goto out_put_dev;
- rcu_read_lock();
- map = rcu_dereference(dev->priomap);
+ map = rtnl_dereference(dev->priomap);
if (map)
map->priomap[prioidx] = priority;
- rcu_read_unlock();
out_put_dev:
+ rtnl_unlock();
dev_put(dev);
out_free_devname:
--
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